Mail Bomb

Mail Bomb is a term used to describe a large number of unwanted email communications sent to a single recipient, or to a group of recipients.  These messages are sent with the intention of crashing the email user’s email program — or to prevent the user from receiving legitimate email communications.  If done to a number of users on the same server, mail bombing can effectively crash the entire server with its heavy load.  Frequently, these mass mailings will target dedicated hosts that handle website and business email accounts; in these cases, the attack can be devastating to the host and the company.

While mail bombs can be detrimental to recipients, this simple DDoS (distributed denial of service) attack can be easily detected by most spam filters.  However, mail bombs are not like spam in that these messages are sent in greater frequency with the deliberate goal of crashing the user’s program or the mail server.  In these attacks, the sender will employ a simple botnet — a hierarchical network of computers controlled by the single malicious sender, similar to systems employed by spammers — to send a great volume of emails. These emails are all addressed to a single user, or to a few users, which the mail bomber wishes to target.